I'm with Troy, just go ahead and jump in!
As far as instant read, I've got the thermopop, but really only use it for chicken. I do the probe test for tenderness on all large cuts. So when I'm doing pork butts or a brisket I use it but it's usually not on.
As far as the leave in thermometer, most of the time I just go with a simple dial oven thermometer that I got at Walmart for like $4, works great! That being said the remote probe one I have I got at Aldis for like $14.
I understand wanting all the toys, there's still a lot on my list too, and being on a budget... I say go get an oven thermometer, and spend the rest on meat.
What are you planning on cooking, might be able to give you more specifics on set up and times.